<?php

/* SVN FILE: $Id$ */
/**
 * SassFunctionDefinitionNode class file.
 * @author      Chris Yates <chris.l.yates@gmail.com>
 * @copyright   Copyright (c) 2010 PBM Web Development
 * @license      http://phamlp.googlecode.com/files/license.txt
 * @package      PHamlP
 * @subpackage  Sass.tree
 */

/**
 * SassFunctionDefinitionNode class.
 * Represents a Function definition.
 * @package      PHamlP
 * @subpackage  Sass.tree
 */
class SassFunctionDefinitionNode extends SassNode
{

    const NODE_IDENTIFIER = FALSE;
    const MATCH = '/^@function\s+([_-\w]+)\s*(?:\((.*?)\))?\s*$/im';
    const IDENTIFIER = 1;
    const NAME = 1;
    const ARGUMENTS = 2;

    /**
     * @var string name of the function
     */
    private $name;

    /**
     * @var array arguments for the function as name=>value pairs were value is the
     * default value or null for required arguments
     */
    private $args = array();
    public $parent;

    /**
     * SassFunctionDefinitionNode constructor.
     * @param object source token
     * @return SassFunctionDefinitionNode
     */
    public function __construct($token)
    {
        // if ($token->level !== 0) {
        //   throw new SassFunctionDefinitionNodeException('Functions can only be defined at root level', $token);
        // }
        parent::__construct($token);
        preg_match(self::MATCH, $token->source, $matches);
        if (empty($matches)) {
            throw new SassFunctionDefinitionNodeException('Invalid Function', $token);
        }
        $this->name = $matches[self::NAME];
        $this->name = preg_replace('/[^a-z0-9_]/', '_', strtolower($this->name));
        if (isset($matches[self::ARGUMENTS])) {
            if (strlen(trim($matches[self::ARGUMENTS]))) {
                foreach (explode(',', $matches[self::ARGUMENTS]) as $arg) {
                    $arg = explode(($matches[self::IDENTIFIER] === self::NODE_IDENTIFIER ? '=' : ':'), trim($arg));
                    $this->args[substr(trim($arg[0]), 1)] = (count($arg) == 2 ? trim($arg[1]) : null);
                } // foreach
            }
        }
    }

    /**
     * Parse this node.
     * Add this function to  the current context.
     * @param SassContext the context in which this node is parsed
     * @return array the parsed node - an empty array
     */
    public function parse($context)
    {
        $context->addFunction($this->name, $this);
        return array();
    }

    /**
     * Returns the arguments with default values for this function
     * @return array the arguments with default values for this function
     */
    public function getArgs()
    {
        return $this->args;
    }

    /**
     * Returns a value indicating if the token represents this type of node.
     * @param object token
     * @return boolean true if the token represents this type of node, false if not
     */
    public static function isa($token)
    {
        return $token->source[0] === self::NODE_IDENTIFIER;
    }

    /**
     * Evalutes the function in the given context, with the provided arguments
     * @param SassContext - the parent context
     * @param array - the list of provided variables
     * @throws SassReturn - if the @return is fired then this is thrown to break early
     * @return SassBoolean(false) - if no @return was fired, return false
     */
    public function execute($pcontext, $provided)
    {
        list($arguments, $context) = SassScriptFunction::fill_parameters($this->args, $provided, $pcontext, $this);
        $context->setVariables($arguments);

        $parser = $this->parent->parser;

        $children = array();
        try {
            foreach ($this->children as $child) {
                $child->parent = $this;
                $children = array_merge($children, $child->parse($context));
            }
        } catch (SassReturn $e) {
            return $e->value;
        }

        return new SassBoolean('false');
    }

}
